Use locally build artifact to build container from public dockerfile

Previously we would build an image (which would not actually be used), build
dockerfiles, modify dockerfiles to curl from
`https://snapshots.elastic.co/downloads/logstash'` then build the image used for
testing based on the modified dockerfile. This resulted in testing the last
published image to `snapshots`. This presents two problems 1. The test is
running against the last published image (not the tip of the branch being
tested) 2. this carries a dependency on both a DRA and unified stack release
having been run. Therefor acceptance tests will fail in between the time we bump
logstash version and a successful run of unified release.

This commit modifies the dockerfile to use the artifact prepared in the first
step instead of curling the last published one. This solves both issues as the
tests run against the code from the tip fo the branch being tested and there is
no dependency on an artifact existing as a result of a unified release pipeline.

Author: donoghuc

docker/Makefile

@@ -142,7 +142,12 @@ build-from-dockerfiles_full: public-dockerfiles_full
 	cd $(ARTIFACTS_DIR)/docker && \
 	mkdir -p dockerfile_build_full && cd dockerfile_build_full && \
 	tar -zxf ../../logstash-$(VERSION_TAG)-docker-build-context.tar.gz && \
-	sed 's/artifacts/snapshots/g' Dockerfile > Dockerfile.tmp && mv Dockerfile.tmp Dockerfile && \
+	cp ../../logstash-$(VERSION_TAG)-linux-$(ARCHITECTURE).tar.gz . && \
+	awk '/# Add Logstash itself and set permissions/{print; print "COPY logstash-$(VERSION_TAG)-linux-$(ARCHITECTURE).tar.gz /tmp/logstash.tar.gz"; next}1' Dockerfile > Dockerfile.tmp && \
+	sed '/curl --fail --location --output logstash.tar.gz.*tar.gz &&/d' Dockerfile.tmp > Dockerfile.tmp2 && \
+	sed 's|tar -zxf logstash.tar.gz|tar -zxf /tmp/logstash.tar.gz|' Dockerfile.tmp2 > Dockerfile.tmp3 && \
+	sed 's|rm logstash.tar.gz|rm /tmp/logstash.tar.gz|' Dockerfile.tmp3 > Dockerfile && \
+	rm -f Dockerfile.tmp* && \
 	docker build --progress=plain --network=host -t $(IMAGE_TAG)-dockerfile-full:$(VERSION_TAG) .
 
 public-dockerfiles_oss: templates/Dockerfile.erb docker_paths $(COPY_FILES)